From the late 1970's through the present day the ability of electronic devices to perform a wide variety of tasks has continually expanded. This is especially true of general purpose digital computing devices which can efficiently process, store and manipulate large quantities of information. As a result, the use of personal computers has proliferated in businesses, homes, academia, and a multitude of other environments. Further, due to more recent advances in technology, the use of portable computers that are compact and relatively light weight so that they may be easily transported from one location to another have become common place.
A main benefit of portable computers is that they may be used while in transport between locations, such as on an airplane, or in a remote location. As used herein, the phase "remote location" means a location that is remote from a source of standard alternating current (AC) power. To enable use in remote locations, portable computers include a battery. Due to the size and weight constraints of portable computers, however, such internal batteries are fairly small in size. As a consequence, they have a limited capacity and typically provide only enough power for three-to-four hours of computer operation. After that, the portable computer must be transported to a source of AC power and the included battery recharged.
Thus, when it is desired to use a portable computer for more than three-to-four hours in a remote location it is now necessary to transport an extended power supply, generally a second external battery, in addition to the portable computer. In this case, when the included battery has been discharged, the external battery is used to power the computer for continued operation. Because the external battery must be portable, it should be compact, relatively light weight and convenient to transport. Further, because the external battery has a finite, although extended, capacity, it should be capable of communicating its charge status as well as other pertinent information to the portable computer.
Various types of external batteries have been used in the prior art. For example, nickel-cadmium and metal-hydride batteries that have a relatively low energy density and are therefore relatively heavy for the amount of power they supply. Thus, they are far from an ideal supply of power for portable applications.
Further the external batteries of the prior art often are not attachable to a portable computer, and thus must be transported as a separate unit. This makes it more difficult for a user to move his or her portable computer/external battery system from one location to another or from one point to another at a given location. Thus, there exists a need for a compact and lightweight external battery that can be attached to a portable computer.
Another problem associated with the external batteries of the prior art is that they supply power to the computer through an external power cord that plugs into an external power port. In such a system, power to the portable computer can be interrupted by a failure in the power cord caused by use over a period of time, by the cord being accidentally pulled out or by the cord's plug becoming loosened from the power port. This is significant because an interruption in the supply of power to a computer can cause a user to lose data. Thus, there exists a need for an external battery with a connection to a portable computer that will not become loosened or fail from use or transport of the computer.
Although portable computers are often able to monitor the state and status of an internal battery, there exists no known external battery that can be monitored by a portable computer in such a manner. Thus, a user cannot monitor the status of the battery directly from the computer as can be done for the included battery. As a result, the computer cannot warn the user of a low charge level in the external battery. Therefore, a need exists for an external battery that is compact, light weight and portable along with a portable computer that provides power in a secure manner and which can be monitored by the computer.